Semiconductor memory device
According to one embodiment, a semiconductor memory device includes a plurality of memory cells; a first circuit configured to convert first data into second data relating to an order of thresholds of the memory cells; and a second circuit configured to perform a write operation on the memory cells based on the second data.
1. A semiconductor memory device comprising:
a plurality of memory cells;
a first circuit configured to convert first data into second data relating to an order of thresholds of the memory cells; and
a second circuit configured to perform a write operation on the memory cells based on the second data,
wherein the second circuit includes a first latch group to store write data, a second latch group to store read data read from the memory cells, and a third latch group to store read data supplied from the second latch group, and performs an arithmetic operation to select a write target memory cell based on the second data.
2. The semiconductor memory device according to claim 1 , wherein the second data includes a plurality of third data items each defining a relationship between thresholds of two memory cells.
3. The semiconductor memory device according to claim 1 , wherein:
a number of latches included in the first latch group is equal to a number of latches included in the third latch group, and
a number of latches included in the second latch group is smaller than the number of latches included in the first latch group or the number of latches included in the third latch group.
4. The semiconductor memory device according to claim 1 , further comprising:
a sequencer configured to control the second circuit, the first latch group, the second latch group, and the third latch group,
wherein when writing the second data in the memory cells, the sequencer:
stores the second data in the first latch group,
performs a first program on the memory cells based on the second data,
performs a verification after the first program,
stores fourth data obtained by the verification in the second latch group,
performs an arithmetic operation on the second data and the fourth data by using the first latch group, the second latch group, and the third latch group, and selects a second program target memory cell, and
performs a second program on the second program target memory cell.
5. The semiconductor memory device according to claim 4 , wherein the second circuit further includes a third circuit configured to perform an arithmetic operation to select the second program target memory cell.
6. The semiconductor memory device according to claim 1 , wherein the second circuit refrains from performing a write operation on only a memory cell in a lowest place of the order of thresholds of the memory cells.
7. The semiconductor memory device according to claim 1 , wherein the second circuit performs a write operation on only a memory cell in a different place of the order of thresholds of the memory cells from the second data.
8. The semiconductor memory device according to claim 1 , wherein when performing a write operation on the memory cells, the second circuit applies different voltages in accordance with the order of thresholds of the memory cells in an initial voltage application.
9. The semiconductor memory device according to claim 1 , wherein the second circuit performs a write operation on each of subgroups which the memory cells are divided into.
10. A memory system comprising:
a controller including a first circuit configured to convert first data into second data relating to an order of thresholds of a plurality of memory cells; and
a semiconductor memory device including the memory cells and a second circuit configured to perform a write operation on the memory cells based on the second data transmitted from the controller,
wherein the second circuit includes a first latch group to store write data, a second latch group to store read data read from the memory cells, and a third latch group to store read data supplied from the second latch group, and performs an arithmetic operation to select a write target memory cell based on the second data.
11. The memory system according to claim 10 , wherein the second data includes a plurality of third data items each defining a relationship between thresholds of two memory cells.
12. The memory system according to claim 10 , wherein:
a number of latches included in the first latch group is equal to a number of latches included in the third latch group, and
a number of latches included in the second latch group is smaller than the number of latches included in the first latch group or the number of latches included in the third latch group.
13. The memory system according to claim 10 , further comprising:
a sequencer configured to control the second circuit, the first latch group, the second latch group, and the third latch group,
wherein when writing the second data in the memory cells, the sequencer:
stores the second data in the first latch group,
performs a first program on the memory cells based on the second data,
performs a verification after the first program,
stores fourth data obtained by the verification in the second latch group,
performs an arithmetic operation on the second data and the fourth data by using the first latch group, the second latch group, and the third latch group, and selects a second program target memory cell, and
performs a second program on the second program target memory cell.
14. The memory system according to claim 13 , wherein the second circuit further includes a third circuit configured to perform an arithmetic operation to select the second program target memory cell.
15. The memory system according to claim 10 , wherein the second circuit refrains from performing a write operation on only a memory cell in a lowest place of the order of thresholds of the memory cells.
16. The memory system according to claim 10 , wherein the second circuit performs a write operation on only a memory cell in a different place of the order of thresholds of the memory cells from the second data.
17. The memory system according to claim 10 , wherein when performing a write operation on the memory cells, the second circuit applies different voltages in accordance with the order of thresholds of the memory cells in an initial voltage application.
18. The memory system according to claim 10 , wherein the second circuit performs a write operation on each of subgroups which the memory cells are divided into.